Spanners

A spanner, or wrench in American English, is a hand tool used to apply torque to turn fasteners such as nuts and bolts. Spanners are designed to grip the hex, square, or other drive shapes of fasteners and transfer force from the user to the fastener. They come in various shapes and sizes to accommodate different fasteners and work environments.

Common types include: Open-ended spanners with two flat jaws; box-end spanners with a closed loop; combination spanners that combine both open and box ends; and adjustable spanners that slide to grip different sizes. Socket spanner sets use a ratchet handle with interchangeable sockets. There are also specialized forms such as C-spanners, spanner wrenches used for retaining rings, and pipe wrenches for gripping cylindrical pipes.

Materials: Most spanners are made from alloy or high-carbon steel and finished with chrome plating or other corrosion-resistant coatings. They are sized in metric millimeters or imperial inches. Standards in different regions regulate dimensions and tolerances, e.g., DIN/ISO in Europe and ANSI/ASME in the United States; JIS in Japan.

History: The term spanner is used primarily in Commonwealth countries; in the United States, wrench is common. The modern adjustable spanner was developed in the late 19th century, with Johan Petter Johansson often credited as a key inventor; pipe wrenches such as the Stillson wrench are a related form designed for gripping pipes.

Usage and care: Use the correct size and type for the fastener to avoid rounding, apply straight torque rather than side load, and avoid overtightening. Keep tools clean and dry, and store in a dry place. For controlled torque, use a torque wrench.